scholarly journals Synthesis, Crystal Structure, Vibrational Study and DFT Computation of Barium Dihydrogenomonophosphate Ba(H2PO4)2

2021 ◽  
Vol 12 (1) ◽  
pp. 1120-1133
Keyword(s):  
Raman Spectra ◽  
Density Functional ◽  
Direct Method ◽  
Structural Parameters ◽  
Molecular Geometry ◽  
Basis Set ◽  
Experimental Investigations ◽  
Infrared And Raman Spectra ◽  
X Ray Crystallography ◽  
Infrared Intensities

The single crystal of barium dihydrogenomonophosphate, Ba(H2PO4)2 was prepared by the direct method. This compound exists in two forms: one orthorhombic, the other triclinic. In this work, we are interested in the triclinic form from the vibrational and crystalline side too. X-ray crystallography showed that this compound crystallizes in the triclinic centrosymmetric with space group P-1 (Z=2) with a = 6.9917(5)Å,b = 7.1929(5)Å,c = 7.9667(9)Å,α = 104.517(8)°,β = 95.918(7)° and γ = 109.459(6). The structure was solved from 3444 independent reflections with R = 0.0198 with wR= 0.0633.The bands observed in the infrared and Raman spectra of Ba(H2PO4)2 are assigned based on the literature results and the theoretical group analyses carried out in the group of factors Ci. The optimal molecular geometry, harmonic vibrational frequencies, infrared intensities, and Raman scattering activities were calculated using density functional theory (DFT/B3LYP) methods with the LanL2DZ basis set. The HOMO-LUMO properties and geometries of this compound have been determined and discussed. The computational structural parameters are generally in agreement with the experimental investigations. The theoretical infrared and Raman spectra for the title compound have been constructed.

Molecular and Electronic Structure of 1-Naphtol : Ab Initio Molecular Orbital and Density Functional Study

2011 ◽  
Vol 110-116 ◽  
pp. 1862-1869
Author(s):  
G. Raja ◽  
K. Saravanan ◽  
S. Sivakumar
Keyword(s):  
Ab Initio ◽  
Quantum Chemical Calculations ◽  
Raman Spectra ◽  
Quantum Chemical ◽  
Density Functional ◽  
Computational Method ◽  
Basis Set ◽  
Mode Analysis ◽  
Functional Study ◽  
Infrared And Raman Spectra

The molecular vibrations of 1-Naphtol were investigated in polycrystalline sample, at room temperature, by FT- IR and FT-Raman spectroscopy. In parallel, ab initio and various density functional (DFT) methods were used to determine the geometrical, energetic and vibrational characteristics of 1-Naphtol . On the basis of B3LYP/6-31G* and B3LYP/6-311+G** methods and basis set combinations, a xnormal mode analysis was performed to assign the various fundamental frequencies according to the total energy distribution (TED). The vibrational spectra were interpreted, with the aid of normal coordinate analysis based on a scaled quantum mechanical force field. The Infrared and Raman spectra were also predicted from the calculated intensities. Comparison of simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes. Simulation of Infrared and Raman spectra, utilizing the results of these calculations led to excellent overall agreement with observed spectral patterns. The investigation is performed using quantum chemical calculations conducted by means of the Gaussian 98W and Guassview set of programs. Further, density functional theory (DFT) combined with quantum chemical calculations to determine the first-order hyperpolarizability.

Density Functional Theory and ab initio Hartree-Fock Calculations of Molecular Structure and Vibrational Spectra of Anilinium Nitrate

2008 ◽  
Vol 63 (10-11) ◽  
pp. 712-720 ◽  
Author(s):  
Davut Avcı ◽  
Adil Başoğlu ◽  
Yusuf Atalay
Keyword(s):  
Molecular Structure ◽  
Density Functional Theory ◽  
Density Functional ◽  
Molecular Geometry ◽  
Vibrational Frequencies ◽  
Basis Set ◽  
Dft Methods ◽  
Functional Theory ◽  
Hartree Fock ◽  
Infrared Intensities

The molecular geometry, vibrational frequencies, infrared intensities, Raman scattering activities and several thermodynamic parameters of anilinium nitrate in the ground state have been calculated by both Hartree-Fock (HF) and three density functional theory (DFT) methods (B3LYP, BLYP and B3PW91) using the 6-31G(d) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray structure. The optimized geometric bond lengths are described very well by the HF method while bond angles are reproduced more accurately by the DFT methods. Comparison between the observed fundamental vibrational frequencies of anilinium nitrate and the results of DFT and HF methods indicates that B3LYP is superior to the scaled HF, BLYP and B3PW91 approaches for molecular vibrational problems. The computed vibrational frequencies are used to determine the types of molecular motions associated with each of the experimental bands observed. In addition, calculated results are related to the linear correlation plot of computed data versus experimental geometric parameters and IR data.

Quantum Mechanical Investigation of Geometrical Structure and Dynamic Behavior of h-BNNT (9,9-5) and h-AlNNT (9,9-5)Single-Walled Nanotubes: NBO Analysis

2019 ◽  
Vol 16 (9) ◽  
pp. 705-717
Author(s):  
Mehrnoosh Khaleghian ◽  
Fatemeh Azarakhshi
Keyword(s):  
Carbon Nanotubes ◽  
Density Functional ◽  
Structural Parameters ◽  
Energy Levels ◽  
Nbo Analysis ◽  
Electronic Energy ◽  
Boron Nitride Nanotubes ◽  
Basis Set ◽  
B3lyp Method ◽  
Mechanical Investigation

In the present research, B45H36N45 Born Nitride (9,9) nanotube (BNNT) and Al45H36N45 Aluminum nitride (9,9) nanotube (AlNNT) have been studied, both having the same length of 5 angstroms. The main reason for choosing boron nitride nanotubes is their interesting properties compared with carbon nanotubes. For example, resistance to oxidation at high temperatures, chemical and thermal stability higher rather than carbon nanotubes and conductivity in these nanotubes, unlike carbon nanotubes, does not depend on the type of nanotube chirality. The method used in this study is the density functional theory (DFT) at Becke3, Lee-Yang-Parr (B3LYP) method and 6-31G* basis set for all the calculations. At first, the samples were simulated and then the optimized structure was obtained using Gaussian 09 software. The structural parameters of each nanotube were determined in 5 layers. Frequency calculations in order to extract the thermodynamic parameters and natural bond orbital (NBO) calculations have been performed to evaluate the electron density and electrostatic environment of different layers, energy levels and related parameters, such as ionization energy and electronic energy, bond gap energy and the share of hybrid orbitals of different layers.

scholarly journals C2: An Asymmetric Specie ?

2020 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Chemical Bond ◽  
Raman Spectra ◽  
Density Functional ◽  
Functional Approach ◽  
Ir And Raman Spectra ◽  
Basis Set ◽  
Ir And Raman

<p> The present work is another contribution to a better understanding of the chemical bond in C<sub>2</sub>. Several density functional approach/basis set provided calculated IR and Raman spectra with simultaneous active bands. Hence, the hypothesis of electronic asymmetry in C<sub>2</sub> [1] was reinforced. </p>

Systematic ab initio study of the compressibility of silicate garnets

2001 ◽  
Vol 57 (2) ◽  
pp. 163-177 ◽  
Author(s):  
V. Milman ◽  
E. V. Akhmatskaya ◽  
R. H. Nobes ◽  
B. Winkler ◽  
C. J. Pickard ◽  
...  
Keyword(s):  
Experimental Data ◽  
Density Functional ◽  
Structural Parameters ◽  
Applied Pressure ◽  
Basis Set ◽  
Ionic Radii ◽  
Cell Parameters ◽  
The Density Functional Theory ◽  
Dodecahedral Site ◽  
Compression Mechanism

The structural properties of the silicate garnets andradite, Ca3Fe2Si3O12, uvarovite, Ca3Cr2Si3O12, knorringite, Mg3Cr2Si3O12, goldmanite, Ca3V2Si3O12, blythite, Mn^{2+}_3Mn^{3+}_2Si3O12, skiagite, Fe^{2+}_3Fe^{3+}_2Si3O12, calderite, Mn^{2+}_3Fe^{3+}_2Si3O12, and khoharite, Mg3Fe^{3+}_2Si3O12, have been investigated with a quantum-mechanical model as a function of applied pressure. The study has been performed with the density functional theory code CASTEP, which uses pseudopotentials and a plane-wave basis set. All structural parameters have been optimized. The calculated static geometries (cell parameters, internal coordinates of atoms and bond lengths), bulk moduli and their pressure derivatives are in good agreement with the experimental data available. Predictions are made for those cases where no experimental data have been reported. The data clearly indicate that the elastic properties of all silicate garnets are dominated by the compressibility of the dodecahedral site. The compression mechanism is found to be based on a bending of the angle between the centers of the SiO4 tetrahedra and the adjacent octahedra, as in the aluminosilicate garnets. An analysis of the relationship between ionic radii of the cations and the compressibility of silicate garnets is presented.

scholarly journals Molecular Geometry, NLO, MEP, HOMO-LUMO and Mulliken Charges of Substituted Piperidine Phenyl Hydrazines by Using Density Functional Theory

2019 ◽  
Vol 32 (2) ◽  
pp. 401-407
Author(s):  
M. Dinesh Kumar ◽  
P. Rajesh ◽  
R. Priya Dharsini ◽  
M. Ezhil Inban
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Molecular Geometry ◽  
Basis Set ◽  
Functional Theory ◽  
B3lyp Method ◽  
Reactivity Descriptor ◽  
Homo Lumo ◽  
Optimized Geometries

The quantum chemical calculations of organic compounds viz. (E)-1-(2,6-bis(4-chlorophenyl)-3-ethylpiperidine-4-ylidene)-2-phenyl-hydrazine (3ECl), (E)-1-(2,6-bis(4-chlorophenyl)-3-methylpiperidine-4-ylidene)-2-phenylhydrazine (3MCl) and (E)-1-(2,6-bis(4-chloro-phenyl)-3,5-dimethylpiperidine-4-ylidene)-2-phenylhydrazine (3,5-DMCl) have been performed by density functional theory (DFT) using B3LYP method with 6-311G (d,p) basis set. The electronic properties such as Frontier orbital and band gap energies have been calculated using DFT. Global reactivity descriptor has been computed to predict chemical stability and reactivity of the molecule. The chemical reactivity sites of compounds were predicted by mapping molecular electrostatic potential (MEP) surface over optimized geometries and comparing these with MEP map generated over crystal structures. The charge distribution of molecules predict by using Mulliken atomic charges. The non-linear optical property was predicted and interpreted the dipole moment (μ), polarizability (α) and hyperpolarizability (β) by using density functional theory.

scholarly journals Structure, electronic properties, NBO, NLO and chemi-cal reactivity of bis (1, 4-dithiafulvalene) derivatives: functional density theory study

2017 ◽  
Vol 6 (1) ◽  
pp. 18
Author(s):  
Tahar Abbaz ◽  
Amel Bendjeddou ◽  
Didier Villemin
Keyword(s):  
Electronic Properties ◽  
Density Functional ◽  
Computational Study ◽  
Molecular Geometry ◽  
Basis Set ◽  
Frontier Molecular Orbital ◽  
Reactivity Descriptors ◽  
Nlo Property ◽  
Functional Density Theory ◽  
Nucleophilic Reactivity

In this work, through computational study based on density functional theory (DFT/B3LYP) using basis set 6-31G (d,p) a number of global and local reactivity descriptors for a series of molecules containing a TTF function which are bis (1,4-dithiafulvalene) derivatives. They were computed to predict the reactivity and the reactive sites on the molecules. The molecular geometry and the electronic properties in the ground state such as frontier molecular orbital (HOMO and LUMO), ionization potential (I) and electron affinity (A) were investigated to get a better insight of the molecular properties. Molecular electrostatic potential (MEP) for all compounds were determined to check their electrophilic or nucleophilic reactivity. Fukui index, polarizability, hyperpolarizability, second order NLO property and natural bond orbital (NBO) analyses have also employed to determine the reactivity of bis (1,4-dithiafulvalene) derivatives.

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